Dynamic tester for projectile components

ABSTRACT

Projectile component testing. A modified projectile, containing components to be tested, is accelerated by means of a vacuum air gun into a spinning tube where it is set in spinning motion while simultaneously being decelerated. Deceleration is accomplished by means of a hydraulic mitigator capable of imparting rotational spin to the projectile while applying a predetermined rate of deceleration. The system is designed for rapid production line testing by means of a control system which starts the spin tube in motion and releases the projectile when a predetermined pressure has been established within the air gun. The control system also terminates the spin and actuates a fluid operated component to replace the mitigator to its start position within the spin tube. In order to provide a check on the polarity of power supplies being tested, a spin angle sensor is provided to transmit a signal for release of the projectile only when the spin tube is in a predetermined angular orientation.

United States Patent [72] Inventor Herbert D. Curchaclr Rockville, Md.[21] Appl. No. 7,929 [22] Filed Feb. 2, 1970 [45] Patented Aug. 10, 1971[73] Assignee The United States of America as represented by theSecretary of the Army [54] DYNAMIC TESTER FOR PROJECTILE COMPONENTS 6Claims, 2 Drawing Figs.

[52] U.S.CI. 73/167,

73/ I2. [51 I Int. Cl G0lm 19/00 [50] Field oiSearch... 73/l67,5, 12;221/233, 257

[56] References Cited UNITED STATES PATENTS 2,462,922 3/1949 Temple221/232 X 3,444,733 5/1969 Curchack 73/167 HEAD OUT I PrimaryExaminer-S. Clement Swisher Assistant ExaminerDenis E. CorrAtt0rneys-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Jv D.Edgerton ABSTRACT: Projectile component testing. A modified projectile,containing components to be tested, is accelerated bymeans of a vacuumair gun into a spinning tube where it is set in spinning motion whilesimultaneously being decelerated. Deceleration is accomplished by meansof a hydraulic mitigator capable of imparting rotational spin to theprojectile while applying a predetermined rate of deceleration. Thesystem is designed for rapid production line testing by means of acontrol system which starts the spin tube in motion and releases theprojectile when a predetermined pressure has been established within theair gun. The control system also terminates the spin and actuates afluid operated component to replace the mitigator to its start positionwithin the spin tube. In order to provide a check on the polarity ofpower supplies being tested, a spin angle sensor is provided to transmita signal for release of the projectile only when the spin tube is in apredetermined angular orientation.

SPIN as FLUID Power $5 =51\ SOUQCE PRESSURE 5PM 'mmsoucerz VACUUM PUMPcomm. SYSTEM DYNAMIC TESTER FOR PROJECTILE COMPONENTS RIGHTS OF THEGOVERNMENT The invention described herein may be manufactured, used, andlicensed by or for the US. Government for governmental purposes withoutthe payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION This invention relates to an apparatus forlinear and angular acceleration to which projectiles are subjected inrifled artillery weaponry, and more particularly to an improvement inthe artillery simulator disclosed in Us. Pat. No. 3,444,733 issued toCurchack'on May 20, I969.

The artillery simulator disclosed in the Curchack patent unites thefeatures of a gas gun and a low,inertia spinner in a single testapparatus to simulate the linear and angular accelerations experiencedin rifled artillery weaponry. Difficulties are encountered in adaptingthe invention disclosed in the Curchack patent to production linetesting of projectile components, such as power supplies and fuzes, inrapid succession. The purpose of this invention is to overcome thesedifficulties and to provide an artillery simulator capable of testinglarge numbers ofprojectile components in rapid succession.

It is therefore a primary object of this invention to provide a testapparatus for simulating the linear and angular accelerationsexperienced in rifle artillery weaponry.

Another object of this invention is to provide a test apparatus which isfully automated and capable of testing projectile components in rapidsuccession.

simulating the SUMMARY OF THE INVENTION Briefly, in accordance with thisinvention, a modified prominates the spin and actuates a fluid operatedcomponent to replace the mitigator to its start position within the spintube. In order to provide a check on the polarity of power suppliesbeing tested, a spin angle sensor is provided to transmit a signal forrelease of the projectile only when the spin tube is in a predeterminedangular orientation.

BRIEF DESCRIPTION OF THE DRAWINGS Thev foregoing and other objects,features and advantages of the invention will be apparent from thefollowing more particular description ofa preferred embodiment of theinvention as illustrated in the accompanying drawings in which:

FIG. I is a diagrammatic representation of a complete system embodyingthe principles of the present invention.

FIG. 2 is a cross-sectional view of one embodiment of a mitigator foruse in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention will be understoodmore readily by referring to FIG. I which shows the entire system indiagrammatic form, Acceleration gun I containing projectile II isprovided with a quick-change diaphragm assembly 26 including a thindiaphragm 14. The acceleration gun is powered by means of vacuum pump 12through valve 13 which is actuated by control system I7. Projectile IIis fired out of acceleration gun by creating a partial vacuum in theforward portion 8 of the acceleration gun, thereby causing atmosphericpressure to act at the rear 9 of the projectile. Restraining pin 15 islocated within groove 16 of projectile II to prevent the projectile frombeing fired until a predetermined pressure has been established withinthe acceleration gun. Pressure transducer I8 detects this predeterminedpressure and transmits a signal to control system I7 which in turn shutsoff valve 13 and withdraws pin l5 to permit the projectile to be fired.

Upon withdrawal of pin I5, projectile ll pierces membrane 14 and impactssurface 28 of mitigator 20, thereby displacing mitigator 20 fromspin-catch tube 19. Mitigator 20 ultimately comes to rest inmitigator-catch tube 2I after striking platform 23 of hydraulicmitigator replacement means 22. Projectile I l comes to rest withinspincatch tube I9 which has already been set in spinning motion by meansof spin motor 35. The precise moment at which the spin motor isactivated depends upon a predetermined pressure within region 3 ofacceleration gun II), which pressure is detected by pressure transducer18 and transmitted as an electrical signal to control system I7.

Spin-catch tube I9 is caused to spin for a predetermined time in themanner more fully described in the previously mentioned Curchack patent.During the flight period of the projectile its velocity is measured bymeans of photocells 25 in a well-known manner as also described in theCurchack patent.

At the termination of the spin period for the spin-catch tube, fluidpower source 37, which may be hydraulic or pneumatic, is activated by asignal from control system 17 to displace piston 39, thereby insertingplatform 23 into mitigatorcatch tube 21. Mitigator 20 is thus replacedto its normal position within spincatch tube I9 and projectile 1] fallsout onto a support member 24 where it is removed by an operator. Theentire cycle is then repeated with the replacement of a new projectilel1 and a new membrane 14. At the start of a new cycle, restraining pin15 and platform 23 are automatically replaced to their original startingpositions in response to signals fromcontrol system 17. Since the entiresystem is fully automated, it is possible to test a great number ofprojectile components under production line techniques.

Referring now to FIG. 2, mitigator 20 comprises an outer hollow housing45 having a first centrally located bore 5] and a second larger bore 59coaxial with the first bore. Shaft 42 rides within bore 51 and isconnected to piston 43 which rides within the larger bore 59. Region 44is normally filled with a fluid of a predetermined known viscosity andthe entire chamber defined by bore 59 is fluid sealed by means ofsuitable O-rings 0r gaskets. The portion of shaft 42 which extendsoutside of housing 45 is provided with enlarged flange or plate 41having a rubber surface 28 firmly secured thereto.

In the normal operation of this device, mitigator 20 is located withinspin-catch tube I9 and is rotating when it is suddenly struck byprojectile II. The force of projectile lI against surface 28 ofmitigator 20 causes shaft 42 to be pushed into housing 45. Becauseregion 44 is filled with fluid, the force exerted against piston 43 bythe projectile is partially transmitted to housing 45. A small space 57is provided between piston 43 and bore 59. As force is exerted againstpiston 43, some of the fluid in region 84 flows through space 57 therebyallowing piston 43 to be further depressed into housing 45. It will beappreciated that the magnitude of linear deceleration provided bymitigator 20 is controllable by simply varying the diameter of bore 59or by changing such other parameters as the density of the fluid withinregion 44 or the size of space 57. The easiest parameter to change is,of course, the density of the fluid. Thus the rate of fluid flow fromright to left will determine the rate and magnitude of the force whichis transmitted to housing 45 and, consequently, the dece leration forceon projectile 11. Spring 47 is designed to return the piston to itsready position and does not have sufficient resistance to materiallyaffect the deceleration force applied to projectile 11 upon impact.

As was previously mentioned, at the time of impact mitigator 20 islocated within spin-catch tube 19 and is spinning at a very rapid rate.Projectile II, on the other hand, is not spinning at the time of impact.Because it is desirable to start projectile II spinning as soon aspossible, mitigator 20 is designed to impart some of its rotational spinto projectile ll. This is accomplished by causing some of the forcecreated by spinning mass 45 to be exerted through shaft 42 upon nonspinning projectile ll. The force created by spinning mass 45 is coupledto shaft 42 by a pin 52 which extends from shaft 42 into housing 45 andis located within a helical groove 53. The purpose of the helical grooveis to provide a gradual transmission of force from housing 45 to shaft42 rather than an instan taneous force. lf pin 52 were merely locatedwithin a slot rather than a helical groove it is very likely that theshear force on pin 52 would break the pin. A more detailed explanationof this feature can be found in applicants copending applicationentitled Hydraulic Mitigator, Ser. No 7,928, filed Feb. 2, l970.

The details ofelectrical readout 64 are fully described in theaforementioned Curchack patent. The arrangement disclosed therein hasone disadvantage in that a test battery or power supply which is faultybecause of reversed polarity would go undetected by the former readoutsystem. In order to detect such faults in power supplies a spin anglesensor 63 is provided. The spin angle sensor transmits a signal tocontrol system 17 whenever spin-catch tube 19 is in a predeterminedangular orientation. Control system 17 is then programmed to releaserestraining pin IE only upon receiving the appropriate signal from spinangle sensor 63 By mathematically calculating the time which would berequired for projectile II to reach spin-catch tube 19, one candetermine the appropriate release time such that projectile II willalways have the same angular orientation will respect to spin-catch tube[9 at its time of arrival. Consequently, any reverse polarity at readout64 would be indicative of a faulty power supply.

It will be appreciated from the foregoing description that thisinvention provides a novel artillery simulator which is capable of rapidand efficient production line testing of projectile components,

It should be understood that I do not desire to be limited to the exactdetails shown and described, for obvious modifications will occur to oneskilled in the art.

I claim as my invention:

1. An artillery simulator for testing projectile components under firingconditions comprising:

a. projectile means having a hollow portion for containing testcomponents;

b. vacuum acceleration means for accelerating said projectile to adesired velocity;

. restraining means located within said acceleration means forrestraining said projectile until a predetermined vacuum has beencreated with said acceleration means;

d. a spin-catch tube positioned to receive said projectile upon itsemergence from said acceleration means;

e. mitigator means normally positioned within said spincatch tube toprovide a predetermined amount of deceleration to said projectile uponimpact;

f. a spin motor for rotating said spin-catch tube in response to apredetermined signal;

. a mitigator-catch tube positioned to receive said mitigator upon itsemergence from said spin-catch tube;

h. mitigator replacement means responsive to a predetermined signal fordisplacing said mitigator from said mitigator-catch tube and replacingit in said spin-catch tube, whereby said projectile is caused to fallonto a support located between said accelerator and said spin-catchtube; and

. a control system responsive to the pressure levels within saidaccelerator for removing said restraining means, activating said spinmotor for a predetermined time, and activating said mitigatorreplacement means.

2. The artillery simulator of claim I wherein said vacuum accelerationmeans comprises means for reducing the pressure in the forward region ofsaid projectile, thereby causing atmospheric pressure to propel saidprojectile.

3. The artillery simulator of claim I wherein said mitigator replacementmeans comprises a fluid actuated piston assembly for driving saidmitigator back into said spin-catch tube.

4. The artillery simulator of claim I further comprising a spin anglesensor for sensing the angular orientation of said spin-catch tube andtransmitting a signal to said control system whenever said spin-catchtube is in a predetermined angularorientation.

5. The artillery simulator of claim 4 wherein said restraining pin isreleased only in response to a signal from said spin angle sensor.

6. The artillery simulator of claim I wherein said mitigator comprisesmeans for applying a predetermined deceleration force and imparting aspin force to said projectilev

1. An artillery simulator for testing proJectile components under firingconditions comprising: a. projectile means having a hollow portion forcontaining test components; b. vacuum acceleration means foraccelerating said projectile to a desired velocity; c. restraining meanslocated within said acceleration means for restraining said projectileuntil a predetermined vacuum has been created with said accelerationmeans; d. a spin-catch tube positioned to receive said projectile uponits emergence from said acceleration means; e. mitigator means normallypositioned within said spin-catch tube to provide a predetermined amountof deceleration to said projectile upon impact; f. a spin motor forrotating said spin-catch tube in response to a predetermined signal; g.a mitigator-catch tube positioned to receive said mitigator upon itsemergence from said spin-catch tube; h. mitigator replacement meansresponsive to a predetermined signal for displacing said mitigator fromsaid mitigator-catch tube and replacing it in said spin-catch tube,whereby said projectile is caused to fall onto a support located betweensaid accelerator and said spin-catch tube; and i. a control systemresponsive to the pressure levels within said accelerator for removingsaid restraining means, activating said spin motor for a predeterminedtime, and activating said mitigator replacement means.
 2. The artillerysimulator of claim 1 wherein said vacuum acceleration means comprisesmeans for reducing the pressure in the forward region of saidprojectile, thereby causing atmospheric pressure to propel saidprojectile.
 3. The artillery simulator of claim 1 wherein said mitigatorreplacement means comprises a fluid actuated piston assembly for drivingsaid mitigator back into said spin-catch tube.
 4. The artillerysimulator of claim 1 further comprising a spin angle sensor for sensingthe angular orientation of said spin-catch tube and transmitting asignal to said control system whenever said spin-catch tube is in apredetermined angular orientation.
 5. The artillery simulator of claim 4wherein said restraining pin is released only in response to a signalfrom said spin angle sensor.
 6. The artillery simulator of claim 1wherein said mitigator comprises means for applying a predetermineddeceleration force and imparting a spin force to said projectile.